From 3b6c88331bcd0531d627fe27de5dbd0ac3165300 Mon Sep 17 00:00:00 2001
From: Tobias Hieta <tobias@hieta.se>
Date: Tue, 21 Feb 2023 16:47:54 +0100
Subject: [PATCH] Revert "[Clang] Implement fix for DR2628"

This reverts commit 368b6832de33b366d4eb155f940e7476daace6a8.

See https://github.com/llvm/llvm-project/issues/60777 for details
---
 clang/lib/Sema/SemaTemplate.cpp |  2 --
 clang/test/CXX/drs/dr26xx.cpp   | 16 +++++++++++-----
 2 files changed, 11 insertions(+), 7 deletions(-)

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index 8df8eadad3fe..c3338e4eaed2 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -2540,8 +2540,6 @@ private:
                                       TInfo->getType(), TInfo, LocEnd, Ctor);
     Guide->setImplicit();
     Guide->setParams(Params);
-    if (Ctor && Ctor->getTrailingRequiresClause())
-      Guide->setTrailingRequiresClause(Ctor->getTrailingRequiresClause());
 
     for (auto *Param : Params)
       Param->setDeclContext(Guide);
diff --git a/clang/test/CXX/drs/dr26xx.cpp b/clang/test/CXX/drs/dr26xx.cpp
index 36aea3982474..e69a151b9d02 100644
--- a/clang/test/CXX/drs/dr26xx.cpp
+++ b/clang/test/CXX/drs/dr26xx.cpp
@@ -14,17 +14,23 @@ using enum E; // expected-error {{unknown type name E}}
 }
 }
 
-namespace dr2628 { // dr2628: yes open
+namespace dr2628 { // dr2628: no, this was reverted for the 16.x release
+                   // due to regressions, see the issue for more details:
+                   // https://github.com/llvm/llvm-project/issues/60777
 
 template <bool A = false, bool B = false>
 struct foo {
-  constexpr foo() requires (!A && !B) = delete; // #DR2628_CTOR
-  constexpr foo() requires (A || B) = delete;
+  // The expected notes below should be removed when dr2628 is fully implemented again
+  constexpr foo() requires (!A && !B) = delete; // expected-note {{candidate function [with A = false, B = false]}} #DR2628_CTOR
+  constexpr foo() requires (A || B) = delete; // expected-note {{candidate function [with A = false, B = false]}}
 };
 
 void f() {
-  foo fooable; // expected-error {{call to deleted}}
-  // expected-note@#DR2628_CTOR {{marked deleted here}}
+  // The FIXME's below should be the expected errors when dr2628 is
+  // fully implemented again.
+  // FIXME-expected-error {{call to deleted}}
+  foo fooable; // expected-error {{ambiguous deduction for template arguments of 'foo'}}
+  // FIXME-expected-note@#DR2628_CTOR {{marked deleted here}}
 }
 
 }
-- 
2.40.0.348.gf938b09366-goog